Wiping film

ABSTRACT

A wiping film having a flexible film backing, and a wiping layer formed on one surface of the backing, wherein the wiping layer is composed of a binder and plastic particles dispersed therein. The wiping film is useful for removing foreign matter and loose lubricant from the treatment surface of a magnetic disk without generating any scratches or fiber particles thereon.

[0001] The present invention relates to a material used for finishingthe surface of a magnetic recording medium, and more particularlyconcerns a wiping film that is used for a cleaning process and aburnishing process carried out on the surface of a magnetic disk.

BACKGROUND OF INVENTION

[0002] In recent years, along with the development of the informationprocessing technology such as computers, magnetic recording media suchas magnetic disks have been widely used as the external memory devicesthereof.

[0003] In general, magnetic disks are formed as follows: a non-magneticbacking such as an aluminum alloy backing and glass backing is subjectedto a sequence of surface treatments such as a lapping treatment, apolishing treatment and a texture treatment so that the surface becomesrough, and on the non-magnetic backing having the roughened surface isformed a magnetic recording layer, and on this magnetic recording layeris further formed a protective film made from carbon, SiO₂, etc.

[0004] After forming the protective film, a film cleaning process iscarried out to remove protrusions formed on the surface of theprotective film and foreign matters on the surface of the magnetic disk.This film cleaning process is generally carried out using an abrasivetape.

[0005] Following the cleaning process, a lubricant of fluorocarbon typeis applied to to the protective film to form a lubricating film, andburnishing is carried out thereon to remove adhered matter such as duston the surface of the magnetic recording medium. In general, thisburnishing is also carried out by using an abrasive film. Thereafter,these are subjected to predetermined tests so as to produce magneticrecording medium in conformity with the standard.

[0006] Conventionally, with respect to films used for film cleaning andburnishing, a lapping film is used comprising abrasive grains such asalumina particles and SiC particles carried on a film made of amaterial, such as polyethylene terephthalate and polyamide. For example,Japanese Patent Laid-Open Publication No. 85628/1997, 71572/1998 and114837/1999 have disclosed a lapping film having such a construction.

[0007] In recent years, in order to increase the memory capacity of amagnetic disk, the formation technique of protective films has beenimproved, and a shift has been made from the sputtering method to thechemical vapor deposition (CVD) method. Accordingly, it has becomepossible to provide a high precision and high quality film with highdensity and very thin film thickness. Moreover, the surface of themagnetic disk after the film formation becomes more uniform and moreclean, thereby making it possible to provide a high quality disk (withless abnormally grown protrusions and reduced number of dust particlesgenerated during the film formation).

[0008] Along with the development of the high quality formation film,the lapping film used for film cleaning and burnishing has been improvedto meet the change so that the average particle size of abrasive grainsused therein, which used to be the level of several μm, has now becomemore finer grains of not more than 0.3 μm.

[0009] However, the lapping film contains hard inorganic particles as anabrasive material, and in the case when irregular protrusions exist onthe surface of a lapping film or when grain detachment, etc. occurstherein, the resulting defect is that scratches occur on the surface ofthe magnetic disk. Moreover, if detached grains remain on the surface ofthe disk, these grains might cause a serious defect in which they areembedded in the disk in the succeeding process.

[0010] Therefore, in recent years when the formation technique of theprotective film has been improved, with respect to a film forsurface-treating the protective film of a magnetic disk, a function forremoving foreign matters by wiping them without causing scratches ratherthan for polishing the surface of the protective film has come to berequired. Moreover, in the case when burnishing is carried out afterformation of a lubricating film, the film needs to have an oil-absorbingcharacteristic in order to remove loose lubricant and render thelubricating film more uniform across the surface of the magnetic disk.

[0011] In other words, the quality required for a surface finishingmaterial for the surface of a magnetic disk has come to change inresponse to the improvement of the film quality and changes in theprocesses in which it is used, and those materials which cause noscratches and can remove foreign matters and loose lubricant have cometo be demanded. That is, although emphasis was put on the polishingfunction conventionally, emphasis now has been put on the removal offoreign-matter (wiping function).

[0012] Japanese Patent Laid-Open Publication No. 66179/1993 discloses acleaning film for surface-treating a protective film of a magneticrecording medium. This cleaning film is made of a woven cloth with verythin fibers, and this is used for removing dust after the abrasiveprocess using a lapping film. Therefore, it contains no abrasive grains,and causes no scratches on the surface of the magnetic disk. However,the very thin fibers tend to be cut due to tension and friction, andonce they are cut, fiber particles come off from the woven cloth.Therefore, the application of this cleaning film instead of the lappingfilm causes a problem in which the treatment surface is contaminated byfiber. For this reason, cleaning films composed of woven cloth with verythin fibers have not been put into practical use yet as a material fortreating a protective film surface of a magnetic recording medium.

[0013] The present invention provides a wiping film for removing foreignmatter and loose lubricant, without scratching and without depositingfibrous debris on the treatment surface. The wiping film may be used inthe treatment of magnetic disks and the like.

SUMMARY OF THE INVENTION

[0014] The invention provides a wiping film having a flexible filmbacking, and a wiping layer formed on one surface of the backing, thewiping layer composed of a binder and plastic particles dispersedtherein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In describing aspect of the preferred embodiment, reference ismade to the FIGURE wherein:

[0016]FIG. 1 is a cross-sectional view of an embodiment of a wiping filmin accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017]FIG. 1 is a cross-sectional view of a wiping film according to thepresent invention. Plastic particles 2 are bonded to a surface of afilm-shape backing 1 by a hardened binder resin 3 to provide a wipinglayer 4. This wiping film is used for removing foreign matter and looselubricant from the surface of a magnetic recording medium, that is,mainly from the surface of the magnetic disk so as to provide a uniformlubricating film formed on the surface of the magnetic disk.

[0018] Film Backing

[0019] The film backing is properly selected from polymer films thathave sufficient strength resistant to tape cleaning and burnishingprocesses as well as strength and heat resistance to coating and dryingprocesses during manufacturing processes, are less susceptible todimensional change, and have flexibility. Polymer films conventionallyused as lapping film backings are preferably used.

[0020] Examples of such polymer films, oriented or unoriented films,include, polyester resins such as polyethylene terephthalate,polybutylene terephthalate and polyethylene naphthalate; polyolefinresins such as high-density polyethylene and polypropylene; polystyrene,polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol,ethylene-vinylalcohol copolymer, polyacrylonitrile, polyamide, acrylicresins mainly composed of materials such as esters of acrylic acid, oresters of methacrylic acid; polyacetal, cellulose derivatives such ascellulose triacetate and cellulose diacetate; and polycarbonate. Inparticular, biaxial oriented films of polyethylene terephthalate andnylon and polyimide film are superior in the coating property of wipingfilm, post-processing property and handling in the actual machine, andare preferably used.

[0021] The film backing preferably have appropriate flexibility. Forexample this film backing has a bend elastic modulus of from 500 to 2000kg/mm² measured according to JIS K 6911 by using a test piece having athickness of 1 mm.

[0022] The film backing generally has a thickness of from 5 to 125 μmand more preferably, 14 to 75 μm.

[0023] Plastic Particles

[0024] In lapping films conventionally used for tape cleaning andburnishing processes on the surface of a magnetic recording medium,inorganic materials such as alumina have been used as components in theabrasive layer. However, in order to prevent scratches on the treatmentsurface, in the wiping film of the present invention, plastic particles,which are softer than the inorganic particles, are used. The combinationof such plastic particles and a binder allows the surface of the wipinglayer to have an uneven irregular structure, thereby providing functionsfor taking in fine foreign matters and particles and for absorbing looselubricant, without causing scratches on the polishing treatment subject.

[0025] The plastic particles preferably have a hardness of M10 to M130in the Rockwell hardness, more preferably, M85 to M105. When theRockwell hardness of the plastic particles is less than M10, the plasticparticles become flattened at the time of the application of the wipingfilm, making it impossible to maintain the irregular structure on thesurface. In this case, it is not possible to obtain the wiping effect.Moreover, the Rockwell hardness exceeding M130 tends to cause scratcheson the treatment surface.

[0026] Although not particularly limited, the plastic particlespreferably have spherical shape. This shape prevents scratches fromoccurring on the treatment surface. With respect to the particle size,the average particle size is preferably in the range of 0.01 to 100 μm,more preferably, 0.1 μm to 10 μm. The average particle size less than0.01 μm fails to form the irregularity corresponding to the surfaceroughness required in designing the surface of the wiping layer of thefilm. The average particle size exceeding 100 μm makes the surfaceroughness of the wiping layer of the film too high, resulting indegradation in the wiping function required for the product. Inparticular, it becomes difficult to take in fine particles in the ordersof nm.

[0027] The material of the plastic particles is preferably selected fromresins having a proper hardness. Examples of the material include:esters of polymethacrylic acid, polystyrene, polyolefin, phenolic resin,epoxy resin, acrylonitrile-butadiene-styrene resin, high-densitypolyethylene resin, urea resin, polyester resin, polyvinylchloride,polyamide and polycarbonate. Moreover, those materials obtained bysubjecting these fine particles to a surface modifying treatment, etc.,for example, those materials obtained by metal-coating these fineparticles or introducing a functional group to these fine particles, maybe used. Furthermore, inorganic particles, such as spherical glass orspherical ceramics, may be mixed into the above-mentioned plasticparticles so as to allow the plastic particles to deposit certainly onthe backing.

[0028] Commercially available plastic particles may be used. For example“CHEMISNOW (trade name)” made by Soken Chemical & Engineering Co., Ltd.is listed.

[0029] Binder

[0030] With respect to the binder, conventionally known thermoplasticresin, thermocuring resin, reactive-type resin, electronic-ray-curingresin, ultraviolet-curing resin, visible-light-curing resin, and amixture of these may be used. Those materials that have been used as thebinder of lapping films may be preferably used.

[0031] With respect to these binders, in the case of thermocuring type,those which can provide a hardness of 15 to 90, more preferably, 50 to85, in the Shore D hardness after having been set at room temperatureare preferably used.

[0032] In the case when thermoplastic resins are used as the binder,those having a softening temperature of not more than 150° C., anaverage molecular weight of 10000 to 300000, and a polymerization degreeof at least 50 to 200, in particular, 200 to 700, may be preferablyused.

[0033] More specifically, examples thereof include;vinylchloride-vinylacetate copolymer, vinylchloride copolymer,vinylchloride-vinylacetate-vinylalcohol copolymer,vinylchloride-vinylalcohol copolymer, vinylchloride-vinylidenechloridecopolymer, vinylchloride-acrylonitrile copolymer, acrylate-acrylonitrilecopolymer, acrylate-vinylidenechloride copolymer, acrylate-styrenecopolymer, methacrylate-acrylonitrile copolymer,methacrylate-vinylidenechloride copolymer, methacrylate-styrenecopolymer, urethane elastomer, nylon-silicon resins,nitrocellulose-polyamide resin, vinylpolyfluoride,vinylidenechloride-acrylonitrile copolymer, butadiene-acrylonitrilecopolymer, polyamide resin, polyvinylbutyral, cellulose derivatives(cellulose acetate butyrate, cellulose diacetate, cellulose triacetate,cellulose propionate, nitrocellulose, ethyl cellulose, methyl cellulose,propyl cellulose, methylethyl cellulose, carboxymethyl cellulose, acetylcellulose, etc.), styrene-butadiene copolymer, polyester resin,polycarbonate resin, chlorovinylether-acrylate copolymer, amino acidresin, various synthetic rubbers, thermoplastic resins, and mixturesthereof may be used.

[0034] In the case when thermocuring resins or reactive-type resins areused as the binder, the coating solution preferably has a molecularweight of not more than 200000, and those which have a molecular weightthat becomes infinite by applying heat and humidifying them after havingbeen coated and dried, through a reaction such as a condensing additionreaction. Moreover, among these resins, those which are not softened ormolten until the resin has been thermally decomposed are preferablyused.

[0035] More specifically, examples thereof include: phenolic resin,phenoxy resin, epoxy resin, polyurethane resin, polyester resin,polyurethane polycarbonate resin, urea resin, melamine resin, alkydresin, silicone resin, acrylic reactive resins (electron-ray curingresin), epoxy-polyamide resin, nitrocellulose-melamine resin, a mixtureof high molecular polyester resin and isocyanate prepolymer, a mixtureof methacrylate copolymer and diisocyanate prepolymer, a mixture ofpolyester polyol and polyisocyanate, urea formaldehyde resin, a mixtureof low molecular glycol/high molecular diol/triphenylmethanetriisocyanate, polyamine resin, polyimine resin, etc. and a mixture ofthese.

[0036] With respect to a curing agent for the thermocuring resin,polyisocyanate is preferably used. Specific examples of polyisocyanateinclude: isocyanates such as tolylenediisocyanate,4,4′-diphenylmethanediisocyanate, hexamethylenediisocyanate,xylylenediisocyanate, naphthylene-1,5-diisocyanate,O-toluidinediisocyanate, isophoronediisocyanate, andtriphenylmethanetriisocyanate, or reaction products of these isocyanatesand polyalcohol, or polyisocyanates of dimer to decamer produced bycondensation of isocyanate chains, or products of polyisocyanate andpolyurethane having isocyanate as a terminal functional group. Themolecular weight of these polyisocyanates has a number average molecularweight of 100 to 20000.

[0037] Preparation of Wiping Film

[0038] The wiping film of the present invention is prepared as follows:a wiping layer containing plastic particles and a binder is formed onone surface of a backing film and this layer is cured. The wiping layeris generally formed by mixing and dispersing plastic particles so as topreliminarily prepare a coating solution, and applying this coatingsolution to the surface of a backing film so as to be dried thereon.

[0039] The plastic particles and the binder is preferably mixed in aweight ratio (particles/binder) of nonvolatile components (that is, atthe state that solvents are excluded, for example, in case of examples,at the state that methyl ethyl ketone, and toluene are excluded) of70/100 to 350/100, more preferably 100/100 to 200/100. When the mixtureratio is less than 70/100, most of the surface of the wiping layer ofthe film covered with the binder, a sufficient irregular structurerequired for the product is not achieved. When the mixture ratio is morethan 350/100, the plastic particles are easily detached from the wipinglayer.

[0040] Upon mixing, a plurality of kinds of binders may be combined andused, and, if necessary, conventional additive agents, such as adispersant, a coupling agent, a lubricant, an antistatic agent, anantioxidant, a moldewproof agent, a colorant and a solvent, may be addedthereto. The addition order of the respective components, the dispersingtemperature (0 to 80° C.), etc. may preferably be controlled.

[0041] The addition order of the additives is, for example, that acoupling agent and a dispersing agent are added at the time when mixingof plastic particles and a binder are started, and a lubricant and anantistatic agent and the like are added coincidentally after uniformdispersion is formed. The dispersing temperature is for exampledetermined in consideration of boiling point of a solvent contained inan coating solution. For example, dispersing process may be carried outwith keeping at 20 to 50° C. in the case that methyl ethyl ketone ortoluene are mainly employed as a solvent. The preparation of the coatingsolution may be carried out by using a conventional kneading machine.

[0042] With respect to the method for coating the backing film with thecoating solution, after the viscosity of the coating solution has beenappropriately adjusted, it is applied through the following methods:gravure coater, air doctor coater, blade coater, rod coater, knifecoater, squeeze coater, impregnating machine, reverse roll coater,transfer roll coater, kiss roll coater, cast coating, spray coater, slotorifice coater (curtain coater, fountain coater), static powder coater,electrodeposition coating, powder electrodeposition coating, vacuumplating method, extrusion coater, micro replication method, PVD method,CVD method, and various vapor deposition methods.

[0043] Specific explanations of these methods are given in “CoatingSystems” published by Maki Book Store (published on Oct. 30, 1979) and“New Trend of Thin-Film Techniques” published by Industrial ResearchAssociation (published on Jul. 15, 1997) on pages 65 to 135. Examples ofa preferred viscosity of a coating liquid for application by using thevarious kinds of coating apparatus are as follows. TABLE 1 Coatingapparatus Viscosity (cps) gravure coater    50 to 10,000 air doctorcoater    50 to 500 blade coater  1,000 to 50,000 rod coater    25 to100 knife coater   500 to 10,000 squeeze coater    50 to 500 reverseroll coater    50 to 100,000 transfer roll coater   500 to 4,000 kissroll coater    50 to 400 cast coater 30,000 to 50,000 spray coater    50to 400 curtain coater   200 to 10,000 fountain coater not more than100,000 electrodeposition coater (only for binder)   100 to 10,000extrusion coater    50 to 100,000 micro replication method    10 to100,000

[0044] The order of application of these coating solutions may bedesirably selected, and prior to a coating by a desired solution, a basecoating layer may be placed, or a corona discharging process, etc. maybe applied in order to improve the adhesive strength to the filmbacking.

[0045] After the coating solution has been applied to the film backing,this is dried and the binder is cured so that a wiping film is obtained.The curing process of the binder is generally carried out by heating.

[0046] In the resulting wiping film, the wiping layer has a thickness offrom 1 to 200 μm, more preferably 2 to 20 μm. The thickness of thewiping layer of less than 1 μm tends to cause an interlayer separationin the wiping layer formed on the backing. The thickness exceeding 200μm causes a great amount of consumption of the materials such as theplastic particles and binder, in comparison with the resulting functionsof the wiping layer, resulting in high costs of the film for thispurpose.

[0047] Moreover, a surface of the wiping layer has a center line averagesurface roughness (Ra) of not more than 50 μm, more preferably 0.01 to 5μm (cut off value: 80 μm). The value exceeding 50 μm causes the surfaceof the wiping layer of the film too rough. Here, in the wiping treatmentsubject such as a magnetic disk, it is demanded that the surfaceroughness is reduced to the nano level and further to the angstromlevel, and in response to this demand, it is of course necessary for thesurface roughness of the wiping layer of the film to be adjusted withhigh precision.

[0048] The features of the preferred embodiment are further illustratedin the following non-limiting examples.

EXAMPLES

[0049] A detailed explanation will be given of the present invention bymeans of the following examples; however, the present invention is notintended to be limited by these. Here, in the examples, “part” and “%”refer to “parts by weight” and “% by weight” unless otherwise defined.

Example 1

[0050] Materials A to D, shown in Table 2, were put into a tank, andthis was dispersed and kneaded for 60 minutes at 1800 rpm by using ahigh-speed mixer, and it was confirmed that the plastic particles hadbeen uniformly dispersed. Thereafter, material E was added thereto, andfurther stirred for 15 minutes. Then, this was filtered, and a coatingsolution having a solid concentration of 35.0% was obtained. TABLE 2Compounding amount Materials of coating solution (parts) A) Resin finePolymethylmethacrylate high-crosslinking powder: 30.0 particles made bySoken Chemical K.K., Trade name: Chemisnow -MR-2HG, Shape: spherical,Average particle size: 2 μm, Gel ratio: not less than 99%, True specificgravity: 1.19, Refractive index: 1.49 B) Binder Saturated polyesterresin, Toyobo, Trade name: 62.9 Vylon 65HS, Solid components: 35.5%,Solvent: MEK (32.5%) + TOL (32.5%), Tensile breaking strength: 57 g/cm²,Tensile breaking extension: 720%, Hardness (D): 57, Specific gravity:1.210, Limit viscosity: 0.77 dl/g, Molecular weight: 20000 to 25000, Tg:14° C., Softening point: 128° C., Color: light yellow C) SolventMethylethylketone 28.7 D) Solvent Toluene 29.0 E) Curing agentPolyisocyanate, Nippon polyurethane K.K., Trade 1.0 name: Colonate-L,NCO content: 12.7 to 13.7%, Appearance: light yellow liquid, Viscosity(Gardner): W-Y, Specific gravity: 1.16 to 1.18, Solid components: 74.0to 76.0%, Solvent: Ethylacetate

[0051] With respect to the film backing, a polyethylene terephthalate(PET) film, made by Teijin K. K., having the following properties wasemployed: serial No.: G2-24, average thickness: 23.3 μm, breakingstrength: longitudinal direction 28 kg/mm²-lateral direction 29 kg/mm²,breaking extension: longitudinal direction 125%-lateral direction 110%,surface roughness (Ra): 0.023 μm, thermal contraction rate (150° C.×30minutes): longitudinal direction 1.8%-lateral direction 0.3%, haze:3.0%, friction coefficient: stationary 0.35-moving 0.33.

[0052] The coating solution was applied to the surface of this filmbacking by using a direct gravure coating method. The application wasset to an amount so as to form a thickness of the wiping layer of 6 μmafter the curing process. Next, this was put in an atmosphere of 40 to130° C. for 5 to 300 seconds so that the coated solution was dried, andthe wiping layer was then cured. After the curing process, the surfaceroughness (Ra) of the wiping layer was measured, and the resulting valuewas 0.203 μm.

[0053] The resulting wiping film was set to a texturing polishingmachine made by Hitachi Electronics Engineering K. K. Then, the surfaceof a 3.5 inch NI—P plated aluminum board was subjected to a wipingprocess under conditions shown in Table 3. The surface roughness of theboard was measured before and after the process. Table 3 shows theresults of the measurements. TABLE 3 Compressing pressure (linearpressure)  13 g/mm Film feed 200 mm/min Processing time  60 seconds

Comparative Example 1

[0054] The same processes as Example 1 were carried out except that aconventional lapping film (abrasive grains: aluminum oxide having anaverage particle size of 0.3 μn, Ra of abrasive layer surface: 0.045 μm)was used, so as to polish the surface of a 3.5-inch NI—P plated Alboard.

[0055] The surface roughness of the board was measured before and afterthe process. Table 4 shows the results of the measurements.

Comparative Example 2

[0056] The same processes as Example 1 were carried out except that aconventional lapping film (abrasive grains: aluminum oxide having anaverage particle size of 1 μm, Ra of abrasive layer surface: 0.162 μm)was used, so as to polish the surface of a 3.5-inch NI—P plated Alboard.

[0057] The surface roughness of the board was measured before and afterthe process. Table 4 shows the results of the measurements.

Comparative Example 3

[0058] The same processes as Example 1 were carried out except that aconventional lapping film (abrasive grains: aluminum oxide having anaverage particle size of 2 μm, Ra of abrasive layer surface: 1.56 μm)was used, so as to polish the surface of a 3.5-inch NI—P plated Alboard.

[0059] The surface roughness of the board was measured before and afterthe process. Table 4 shows the results of the measurements. TABLE 4Before polish After polish Ra (nm) Rz (nm) Ra (nm) Rz (nm) Example 2.324.3 2.3 22.9 Comparative 2.3 24.3 3.1 45.3 Example 1 Comparative 2.324.3 6.4 80.4 Example 2 Comparative 2.3 24.3 10.3 115.1 Example 3

[0060] In the case of the surface treatment carried out by the wipingfilm of the example, the surface roughness of the board was not changedbefore and after the treatment, and it was confirmed that the treatmentsurface was free from damages such as scratches.

[0061] The wiping film of the present invention does not containinorganic particles nor fiber materials so that it generates neitherscratches nor fiber dusts on the treatment surface. Moreover, it has anuneven irregular structure on the surface so that it is possible toremove foreign matters and loose lubricant from the treatment surface.

1. A wiping film comprising a flexible polymer film backing, and awiping layer formed on a surface of the backing, the wiping layercomprising a binder with plastic particles dispersed therein.
 2. Thewiping film according to claim 1, wherein the plastic particles have anaverage particle size of from 0.01 to 100 μm, and a Rockwell hardness offrom M10 to M130.
 3. The wiping film according to claim 1 to 2, whereinthe plastic particles and the binder are contained in a weight ratio offrom 70/100 to 350/100.
 4. The wiping film according to any one ofclaims 1 to 3, wherein a surface of the wiping layer has a center lineaverage surface roughness (Ra) of not more than 50 μm.
 5. The wipingfilm according to any one of claims 1 to 4, wherein the polymer filmbacking comprises polymers selected from the group consisting ofpolyester resins, polyolefin resins, polystyrene, polyvinyl chloride,polyvinylidene chloride, polyvinyl alcohol, ethylene-vinylalcoholcopolymer, polyacrylonitrile, polyamide, acrylic resins, polyacetal,cellulose derivatives, and polycarbonate.
 6. The wiping film accordingto any one of claims 1 to 4, wherein the polymer film backing has a bendelastic modulus of from 500 to 2000 kg/mm² measured according to JISK6911 by using a test piece having a thickness of 1 mm, is biaxiallyoriented and comprises polymers selected from the group consisting ofpolyethylene terephthalate, nylon and polyimide.
 7. The wiping filmaccording to any one of the claims 1 to 6, wherein plastic particlescomprise materials selected from the group consisting of esters ofpolymethacrylic acid, polystyrene, polyolefin, phenolic resin, epoxyresin, acrylonitrile-butadiene-styrene resin, high-density polyethyleneresin, urea resin, polyester resin, polyvinylchloride, polyamide andpolycarbonate.
 8. A method of treating the surface of a magneticrecording medium comprising applying a wiping film to the surface ofmagnetic recording medium to clean the surface, the wiping filmconstructed according to any one of claims 1 to 7.